P-Heterocyclics

Borane complexes of P-heterocycles as versatile precursors for the synthesis of chiral phosphine ligands used for asymmetric catalysis 98S1391. 

Kabachnik-Fields reaction in synthesis and transformations of P-heterocycles 98UK940. 

Chiral P-heterocycles as P-mono- and P,N-bidentate ligands in the synthesis of coordination compounds and homogeneous asymmetric catalysis 98KK883. 

Applications of oxazaphospholidine-borane complexes, cyclic phosphoramides, compounds with N—P=0 function, and other P-heterocycles in enantio-selective catalysis 99SL377. 

Syntheses of five- and six-member P-heterocycles from 1,4- and 1,5-diketones 98IZV1905. 

Phosphinine Derivatives and their Use as Versatile Intermediates in P-Heterocyclic... 

The phosphacyclopentadienes with phosphine function are called 1//-phospholes and they form an important part of contemporary P-heterocyclic chemistry. Phosphole chemistry has undergone an intensive development, which is well demonstrated by the fact that while in the first edition of Comprehensive Heterocyclic Chemistry (1984), only several pages were devoted to phospholes [1], the second edition (1996) discusses this topic in a lengthy chapter [2], Besides these, exhaustive monographs have been published in P-heterocyclic chemistry also incorporating the new developments of phosphole chemistry [3, 4], The first review in the subject was written by Mathey [5],... 

At the Department of Organic Chemistry and Technology, Budapest University of Technology and Economics, we have been dealing with the synthesis and utilization of P-heterocycles for more than two decades. In this chapter, the synthesis and properties of phospholes with bulky substituent on the phosphorus atom are described. 

One may consider phospholes to belong to the family of five-membered P-heterocycles pyrrole, furan, and thiophene. A significant difference, however, is that the phospholes described in the literature display only a slight extent of aromaticity. This is well demonstrated by the comparison of the Bird-indexes [32] of benzylphosphole [33], furan, pyrrole, and thiophene (Fig. 1). The Bird-index is an indicator of aromaticity based on the bond-equalizaton. It is the maximum (100) for benzene. 

The validity of the Hammett relationship log K/K0 = pa, has been extensively investigated for five-membered heteroaromatic compounds and their benzo analogues. The ratio p(heterocycle) / p(benzene) is closest to unity for thiophene. Judged from work on the polarographic reduction of nitro compounds, the ability to transmit electronic effects is HC = CH = S < O < NH. 

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